It is common practice to install steel reinforcing bars (re-bar) to strengthen concrete structures. Typically, a project design engineer will specify the size, number and type of re-bar to be used, and determine the precise locations within the structure that each re-bar is to be located. On the job-site, the tradesmen must measure and place the re-bar within a concrete form such that, after the concrete is poured into the form and cured, the re-bars will be properly located within the finished concrete structure in accordance with the engineer's specifications.
The correct placement of re-bar within the form requires precise measurement and careful placement of re-bars within the form. Re-bars are typically tied together using steel wires to keep them in place. However even with these precautions, re-bars can be dislodged both before and during the poring of the concrete. Various means have been proposed to securely support re-bars at the desired locations within a concrete form, and to prevent unintentional movement of the re-bar during the concrete pour.
U.S. Patent Application Publication No. 2007/0209310 (Papke) discloses a device for supporting multiple re-bars at a predefined spacing. The device described by Papke comprises a concrete beam member having recesses or saddles at predefined locations for holding re-bars. Each saddle is associated with a pair of wires embedded in the beam member for securing a re-bar in place. The very high weight of concrete increases costs to manufacture and use Papke's beam member. In addition, it is not possible to place multiple beam members end-to-end while maintaining an accurate spacing between recesses of adjacent beam members. Nor is it practical to secure Papke's concrete beam members in a vertical mould such as for a wall.
U.S. Design Pat. No. D483246 (McPherson et al.) discloses a re-bar support which comprises an elongated beam member having integrally formed clips for holding re-bars at a fixed spacing determined by the locations of the clips. The use of integrally formed clips severely limits the range of different sizes of re-bars that can be securely held.
U.S. Pat. No. 5,664,390 (Sorkin) discloses an elongated support beam member which includes a plurality of saddles for maintaining re-bars at a predetermined spacing. Two or more of these beam members can be connected together end-to-end using a mating prong and cup at opposite ends of the beam member. Once re-bars have been laid in the desired saddles, each re-bar can be tied in place using wire to prevent movement of the re-bars during a subsequent concrete pour. Wire ties are time-consuming to install properly, and thus increase labor costs.
Techniques that overcome limitations in the above-noted prior art remain highly desirable.